Right
Set Right [ n ]
(Default: same as Set Length)
(Initially: same as Set Length)
Set Right fixes a right margin for listing and editing lines in your workfile. Any existing data to the right of the margin is retained unchanged while you edit to the left of the margin. Set Right also resets the Set Window columns. See Set Left for setting the other margin.
Remember, the left and right margins apply to most commands, including Visual and Keep. To reset the margin to the far right edge, Set Right with no parameter.